As a new generation communications technology standard, long term evolution (LTE) is increasingly widely applied. In an LTE system, a hybrid automatic repeat request (HARQ) technology is used to ensure correct data sending and receiving between a base station and a user terminal. The HARQ is a combination of an automatic repeat request (ARQ) and forward error correction (FEC), that is, to use an automatic repeat request protocol and a forward error correction technology to ensure reliable data transmission. When a data packet arrives at a receive end, error detection is performed on the data packet. If the data packet is correctly received, an acknowledgement (ACK) signal is returned and is denoted by a bit ‘0’; or if the data packet is incorrectly received, a negative acknowledgement (NACK) signal is returned and is denoted by a bit ‘1’. The ACK signal and the NACK signal are collectively referred to as HARQ bits, or may be referred to as HARQ feedback bits and HARQ responses. When receiving the ACK signal, a transmit end may send new data; otherwise, the transmit end may need to retransmit the previously transmitted data packet.
A downlink HARQ refers to a procedure in which a terminal needs to determine whether data delivered by a base station is correctly received. In a current carrier aggregation technology for a plurality of carriers, a dynamic HARQ codebook is usually used to reduce a size of a HARQ feedback codebook. However, when downlink transmission includes a physical downlink shared channel (PDSCH) transmission in a configured periodic semi-persistent scheduling (SPS) subframe, a current dynamic HARQ codebook cannot make a response concerning whether data of SPS downlink transmission is correctly received.